The present invention relates to accurate measurement of signals, and more particularly to the trace delay error compensation where measurements are taken from points remote from the signal source or receiver.
Signals being emitted by a source or received by a receiver generally are measured at the point of origin or point of reception, especially where timing is important at the source or receiver. In the past measurement instruments have been able to probe the signals at such points. However as circuits increase in performance, minimizing capacitive loading of the instrument probe on the circuit being tested to reduce the effect of the probe on circuit performance has become a critical product characteristic. Therefore connection adaptors and lead-sets are being eliminated, and instead connection is made directly with the circuit via connection patterns integrated directly into the circuit, commonly referred to as “connectorless probes.” These connectorless probes reduce the capacitive load on the circuit being tested to less than one picoFarad.
Using a connectorless probe, however, places the point of measurement at a location that is remote from both signal sources and receivers. Further, due to the limits of signal routing on a circuit board, different time delays may be incurred by signals as they propagate between the source, receiver and connectionless probe. These various physical delays result in measurements that are less useful for verifying signal timing at the source or receiver. Also the signals may be distorted along the propagation paths so an accurate analog representation of the signal at the source or receiver also is compromised. Such distortions result in a time shift of the information carried by the signal, further affecting the verification of signal timing at the source or receiver.
Therefore what is desired is a method of trace delay compensation that restores the timing of information carried by signals as they occur at a source or receiver when measured at a remote location.